U.S. Pat. No. 4,728,264 discloses a fuel delivery system for an internal combustion engine that includes an electric-motor fuel pump for delivering fuel under pressure from a fuel tank or supply to an engine. A pressure switch is coupled to the fuel line between the pump outlet and the engine, and is responsive to fuel pressure for opening a pair of switch contacts when such fuel pressure exceeds a predetermined threshold, and closing the contacts when fuel pressure is below such threshold. The pressure switch may be separate from or incorporated into the motor/pump. The contacts of the pressure switch are connected to apply d.c. power to the fuel pump motor when the switch contacts are closed, and to remove power from the pump motor when the contacts are open. In this way, electrical power is applied to the pump motor when pump outlet pressure is below the threshold of the pressure switch, and is removed when outlet pressure exceeds switch threshold pressure.
U.S. Pat. No. 4,789,308 discloses a fuel delivery system for an internal combustion engine in which outlet pressure of an electric-motor fuel pump is monitored by a pressure sensor mounted on the pump outlet end cap. The sensor, which includes a magnet biased by a spring against outlet pressure within the pump housing and a Hall sensor responsive to magnet position, provides a continuous output within the range of the sensor. D.c. power is applied to the pump motor as a continuous function of the sensor output signal.
U.S. Pat. No. 4,951,636 discloses a fuel delivery system in which a pressure sensor is responsive to a pressure differential between fuel pressure at the engine and engine air intake manifold pressure for controlling a pulse-width modulated drive signal applied to the pump motor. The pressure sensor and the motor drive electronics are mounted within a module that includes a passage for fuel flow to the engine so that heat generated by the drive electronics is at least partially dissipated to the fuel.
Although the fuel delivery systems disclosed in the noted patents, all of which are assigned to the assignee hereof, address problems theretofore extant in the art, further improvements remain desirable. A general object of the present invention is to provide a fuel delivery system with pump outlet pressure regulation having improved stability over a wide range of operating conditions. Another object of the invention is to provide a fuel delivery system, and particularly a self-contained electric-motor fuel pump with outlet pressure regulation adapted for use in such system, that is economical to implement in mass production, and is reliable over an extended operating lifetime.